Hydraulic controller for strip material feeder

ABSTRACT

An apparatus is described for intermittently feeding strip material to a punch press or like machine and including a reciprocal carriage member having material grippers provided thereon. The carriage member is reciprocated by way of an air or hydraulic cylinder and the stroke of the carriage cylinder is controlled by means of a counteracting hydraulic plunger cylinder connected to a closed hydraulic system.

United States Patent 11 1 11] 3JMEA8 Aylesworth June 26, 1973 [54] HYDRAULIC CONTROLLER FOR STRIP 3,523,632 8/1970 Shields 226/150 MATERIAL FEEDER 3,429,493 2/1969 Lehmann 226/150 [76] Inventor: Albert Orser Aylesworth, 3050 P nmary Exammer-Allen N. Knowles Alexapder Boulevard Wmdsor Assistant Examiner-Gene A. Church Ontano Canada r a r r 4 Attorney- Peter Kirby, Norris M. Eadcs et al. [22] Filed: Oct. 14, 1971 [21] Appl. No.: 189,237 [57] ABSTRACT An apparatus is described for intermittently feeding 52 US. Cl 226/145, 226/150, 226/162 strip material w punch press or like machine and 51 1111. C1 B65h 17/44 cluding a reciprocal carriage member having material 58 Field of Search 226/143, 150, 15s, pp provided there'on- The carriage member is w 22 159 1 2 145 ciprocated by way of an air or hydraulic cylinder and the stroke of the carriage cylinder is controlled by [56] R f n s it means of a counteracting hydraulic plunger cylinder 7 UNITEDSTATES PATENTS connected to a closed hydraulic system. 3,580Q449 5/1971 Chaban 226/162 X 13 Claims, 4 Drawing Figures a; H E? g n 1= i 'fi HYDRAULIC CONTROLLER FOR STRIP MATERIAL FEEDER This invention relates to a device for feeding strip material, preferably from a coil, to a press or similar work machine.

BACKGROUND OF THE INVENTION A variety of devices have long been known for feeding stock materials to punch presses, stamping machines and the like. They generally include a power operated device for gripping the stock, usually in strip form, and moving it into the press where it is held while the gripping device is retracted for another stroke. The gripping device is usually actuated by means of a double acting piston cylinder with means for varying the feed stroke as required by different jobs. Various means have been provided for cushioning the feed stroke at the end of its travel so that it does not pound against the framework supporting it. It is also commonplace to use a self-actuating wedge-lock which serves with the cushioning= means to prevent work slippage and rebound. However, there have always been major problems with these devices because of the difficulties in trying to provide a proper cushioning affect and avoiding rebound. It will be appreciated that many of these machines may process millions of pieces per year so that even small inaccuracies in measurement of the length of the stroke can result in very substantial material losses through a production year. Moreover, the impact vibrations normally associated with such machines continuously cause loosening of bolts and general wear on the machines. v f A very recent attempt at improving the precision and accuracy of such machines is described in Shields US. Pat. No. 3,523,632 issued Aug. ll, 1970. That machine included an air operated buffer or damper in the work carriage. which was disposed for service at the ends of its forward and return strokes to enable fast operation without jarring effects causing work stock slippage in the grippers on the carriage and base frame. This system included a relatively simple double acting piston member with separate air bleed controls by which the cushioning effect at different ends of the carriage travel could be adjusted as best suited needs and requirements. However, even this system did not provide a completely accurate means for stopping the forward movement of the grippers at a precise location.

In St. Denis copending US. application Ser. No. 150,046 filed June 4, 1971, an electronic control device -is described which very accurately measures a length of strip material being moved through a feeder. Although this system was capable of extreme accuracy in actually measuring the amount of material, this accuracy was lost when it was applied to the usual grippertype feeders because of the bounce effect at the end of the gripper stroke. i

, It is, therefore, the object of the present invention to provide an improved control system for gripper-type feeders whereby the grippers can be stopped at a precise predetermined location.

SUMMARY OF THE INVENTION In the present invention a power cylinder, e.g. an air or hydraulic cylinder, is used to reciprocate the gripper carriage for advancing the strip material. Also connected to the carriage is a double acting hydraulic control cylinder which is connected to a closed fluid system. This closed fluid system is connected to both ends of the hydraulic control cylinder and includes one conduit connecting the two ends of the cylinder which passes through a controllable valve and a second conduit connecting the ends of the cylinder which passes through a spring loaded check valve. With this arrangement full air or hydraulic pressure is maintained on the gripper carriage cylinder at all times and, for instance, when the power cylinder is moving the gripper carriage to advance the strip material, the gripper carriage is pushing the plunger in the hydraulic control cylinder whereby fluid flows from one end of the hydraulic control cylinder to the other through the controllable valve. When the gripper has travelled a predetermined desired distance, the controllable valve closes thereby stopping the flow of fluid in the control circuit and hence stopping the movement of the gripper even though pressure is still being applied through the gripper carriage cylinder. During the return stroke of the gripper carriage cylinder, the fluid in the control system is forced to flow in the opposite direction by the carriage moving the plunger and during this time it flows through the spring loaded check valve. When the flow in that direction stops the spring instantaneously closes thecheck valve and it, of course, remains closed while the fluid flow is in the reverse direction.

Since the stopping of the forward motion of the grippers is entirely controlled by control of flow in a hydraulic system, it will be evident that all of the previous problems of the pounding of the gripper carriage against an abutment in the carriage frame is eliminated. Moreover, this provides for extremely accurate measurement of the forward movement of the gripper whereby it can be controlled from an electrical control system.

DESCRIPTION OF PREFERRED EMBODIMENTS According to a particularly preferred embodiment of the invention, a pair of controllable valves are provided in the hydraulic control system. When the two valves are used, the first valve has a large flow opening and the second valve has a small flow opening. These are arranged such that during a substantial portion of the forward stroke of the gripper carriage, the fluid flows through both valves so that there is little fluid resistance in the control system against the stroke of the gripper carriage cylinder. At a point near the end of the forward stroke of the gripper carriage cylinder, the large first hydraulic control system valve closes so that fluid flow continues only through the small second valve. This has the effect of instantaneously slowing the movement of the gripper carriage to a slow speed. At the point where the gripper carriage is to come to a full stop, the second valve closes so that the fluid flow is completely stopped and the carriage instantaneously comes to a full stop. This is particularly valuable where very high speed short strokes are being used and the combination of the slowdown and complete stopping provides for exceptionally accurate control of the distance of travel of the gripper.

The controllable valve can be actuated by means of a solenoid, pneumatic diaphragm motor,'etc. and can be very simply controlled from limit switches which are actuated by the gripper carriage during its movement or the valves can be connected to an electronic controller such as that described in copending'application Ser.

No. 150,046. The limit switches can be electric, pneumatic, etc.

According to another preferred feature of this invention, the system can be controlled such that the gripper can stop and start several times during a complete stroke of its actuating cylinder. For example, the gripper carriage cylinder may have a stroke of thirty inches and it is desired to produce a series of parts from the strip material each having a length of six inches. In such a situation the gripper can be stopped and started five times during its single stroke whereby five individual workpieces are produced during the single stroke of the gripper. This not only saves in time but greatly saves in general wear and tear on the machine.

DESCRIPTION OF THE DRAWINGS The invention is further illustrated by the attached drawings in which:

FIG. 1 is a side elevation of an apparatus embodying the invention;

FIG. 2 is a plan view of the device shown in FIG. 1;

FIG. 3 is a schematic diagram of the hydraulic and air circuits used in the invention, and

FIG. 4 shows an electronic control systems for use with the invention.

DETAILED DESCRIPTION The device of this invention is used with presses, stamping machines and the like production machines, which have a vertically reciprocal ram acting relative to a platen on which the work stock is received, while the ram is raised, and is adapted to feed the stock into the machine automatically and in timed sequence with the operation of the production machine. Accordingly, it is located near to the production machine to support the work stock as it is fed across the platen at a predetermined distance, in timed sequence with the raising of the ram, as required for the size of the workpiece being formed.

A base or frame member is provided of sufficient length to support and align the work stock being fed into the production machine and with suitable guides at opposite ends for a side edge of the strip or feed material to keep it straight. A carriage member, on guide rails between the ends of the base frame, is moved back and forth by a double acting piston cylinder and is formed to receive and grip the stock material as it is moved forward, release it at the end of its forward stroke, and return for successive work feeding strokes.

The gripper provided on the carriage member is usually operated by a solenoid controlled air valve and a similar gripper with like controls is usually provided on the base frame to hold the work stock while the carriage member is returned for its next Work feeding stroke. 7

Referring now to the drawings, FIG. 1 shows a typical device embodying the invention and comprising a base 10 which has a carriage 13 thereon that supports one or more gripping cylinders 16 to feed the strip material 17 toward a work device such as a press (not shown). The apparatus further includes a front retainer cylinder 12 which operates to grip the strip when the gripping cylinders release the strip and to hold the strip until the gripping cylinders 16 are returned to their original position for another feed stroke. The carriage 14 normally travels on guide rods which are not shown.

Three double acting piston cylinders 15a, 15b and 15c are connected to a common plate 18 on the carriage 13 by piston rods 14. These cylinders 15 are fixed to the base 10. Cylinders 15a and are a pair of air or hydraulic cylinders which act together to reciprocate the carriage 13, while cylinder 15b is a hydraulic cylinder which is connected to the base 10 and plate 18 in the same manner as cylinders 15a and 150. A support member 11 is also shown for the incoming strip material.

Referring now to the hydraulic circuit shown in FIG. 3, one end of cylinder 15b is connected to a hydraulic line 20 which in turn connects to a second line 21. Extending upwardly a distance above the entire system is a hydraulic fluid reservoir 22 which also connects to the line 21, The line 21 is connected by line 23 to a first solenoid operated valve 24 which has a relatively large flow opening. A second line 25 connects line 21 to a second solenoid operated valve 26, which has a relatively small flow opening. The volume of flow through valve 26 can be controlled by providing an additional manually controllable flow valve 41 in line 25 in advance of valve 26. By adjustment of valve 41 the rate of slow down travel of the carriage can be controlled. If desired, a similar type of valve can be installed in line 23 in advance of valve 24 to control the rate of high speed travel of the carriage. Outlet lines from the two solenoid valves connect to line 27 which returns to the opposite end of hydraulic cylinder 15b. A bypass line 29 is also connected between line 21 and line 27 and in this bypass line is connected a spring loaded check valve 30. This valve is arranged to permit flow of fluid only in the direction of the arrow. Thus, it will be seen that the hydraulic cylinder 15b together with its connecting lines and components form a closed hydraulic system which because of the elevated reservoir 22 is always completely filled with fluid.

It will be understood that line 20 can be eliminated and the apparatus will still operate. Thus, the end of cylinder 15b normally connected to line 20 is simply vented to the atmosphere and all of the fluid forced out of cylinder 15b by the plunger is received in reservoir 22.

The air or hydraulic cylinders 15a and 15c are connected in parallel by way of air or fluid lines 32 and 33. These two lines join the opposite ends of cylinders 15a and 150 through a solenoid valve 34 which on signal reverses the direction of air or fluid flow through the cylinders. The system is supplied with regular factory compressed air or fluid from a pump through line 35.

The solenoid valve 34 is electrically connected to the machine being fed by the feeder so that it will advance a length of strip material in synchronized sequence with the cycle of the machine. It is, of course, also operatively connected in known manner to controls for the grippers so that the grippers will also open and close in a synchronized manner with the operation of the solenoid valve and the subsequent machine.

When cylinders 15a and 15c are hydraulically powered, this hydraulic power can be conveniently supplied by a pump driven by a small electric motor. The hydraulic power system also includes a fluid reservoir and a pressure release valve. This pressure release valve limits the maximum pressure in the system so that when control valve 24 closes. the sudden increase in pressure created in the hydraulic drive system is released through the release valve into the reservoir. The

release valve may conveniently be set for a maximum pressure of 200 p.s.i.

The solenoid valves 24 and 26 of the hydraulic control system can be operated either by limit switches or by means of an electronic measuring and controlling system. When they are operated by limit switches, a pair of such switches LSl and LS2 are positioned in the path of travel of the carriage 13 whereby limit switch LS1, which is connected to solenoid valve 24, is tripped to actuate valve 24 and thereby slow down the motion of the gripper and limit switch LS 2 is positioned at the desired end of the travel of the carriage 13 whereby when the carriage trips switch LS2 the valve 26 closes thereby instantaneously stopping the forward advance of the carriage 13. This system is perfectly satisfactory for use in a machine which is designed for the manufacture of a single part.

Of course, many machines manufacture a great variety of different parts and therefore must have complete versatility. When such versatility is required, a measuring and controlling system as shown in FIG. 4 is utilized. As shown in this Figure, a measuring wheel of predetermined diameter 36 is mounted on a shaft 37 with the shaft and wheel being spring loaded so as to press against the top surface of the strip material 17 being advanced by the grippers. A support roller 38 can be positioned below wheel 36 so that firm contact between the wheel and strip material 17 is assured. Thus, the forward movement of the strip material causes the rotation of the wheel 36 and shaft 37. The shaft is connected to a photo-electric rotary transducer 39 for generating electric pulse'data proportional to the rotation of the measuring wheel 36. There is a direct connection between the axle 37 and the transducer 39 so that the transducer will always directly respond to any rotational movement of axle 37 and measuring wheel 36.

An electrical counter 40 is mounted at a convenient location on one side of the machine and is electrically connected to the transducer 30.-

The electric counter has two series of preset control buttons and each control button has a series of calibrations. Each of the two series of preset knobs is arranged to activate a'separate relay.

The electric counter has a typical terminal board with connections for the first and second relay outputs, signal input, external-reset, etc. The outputs from the first and second relays are connected to the solenoid valves 24 and 26.

With this arrangement the electronic counter is sim ply preset for the point at which the carriage is to slow down and the point at which the carriage is to come to a full stop. With this arrangement even though there may be some slippage between the gripper and the strip material because of material unevenness, the gripper will still continue to move forward until such time as the correct amount of strip material has been advanced as indicated by the measuring wheel. When the correct amount of actual strip material has advanced, the signal will be transmitted to the solenoid valves 24 and 26 to slow down and then completely stop the forward movement of the'grippers. 1

This system is particularly well adapted for use in a procedure in which the gripper carriage and strip material stop and start several times during a single forward stroke of the air cylinder. With prior devices, when pieces were being formed which had a length only a fraction of the total possible stroke of the air cylinder,

it was still necessary for the cylinder to go through a complete cycle for each forward movement.

It is also to be appreciated that it is within the scope of this invention to utilize only one controllable valve in the hydraulic control circuit. When only one valve is used there is, of course, no preliminary slow down of the gripper carriage and it is brought to a full stop in a single motion. While the single valve may slightly decrease that accuracy of the step, it will be evident that it still provides all of the other advantages inherent in this system, such as the quietness and smoothness of operation and even a high degree of accuracy as compared to most commercially available machines.

Moreover, although two air or hydraulic cylinders are shown to drive the gripper carriage, the two are used only as a convenient means of providing a smooth motion. Thus, it is entirely within the scope of the present invention to utilize only one air or hydraulic cylinder to drive the gripper carriage.

I claim:

1. In a device for intermittently advancing strip material into a production machine and including a base having a carriage member slidably mounted thereon, a gripper on said carriage member for engaging and holding strip material thereto and power cylinder means mounted on said base for slidably reciprocating said carriage member, the improvement which comprises:

a. a double acting hydraulic plunger-cylinder means connected between said carriage and base, whereby movement of the carriage causes relative movement between the plunger and cylinder,

b. a first fluid conduit connecting opposite ends of said hydraulic cylinder and including check valve means,

c. a second fluid conduit connecting opposite ends of said hydraulic cylinder and including first controllable valve means, and

d. first means for closing said controllable valve when a predetermined length of strip material has been advanced by the gripper carriage, whereby during advance of the gripper carriage, movement of the plunger causes flow of fluid through the second conduit and controllable valve until the valve is closed thereby stopping the plunger and carriage and during return of the carriage, movement of the plunger causes flow of fluid through the first conduit and check valve.

2. A device according to claim 1 which includes a third fluid conduit connecting opposite ends of said hydraulic cylinder, second controllable valve means in said conduit and second means for closing said valve when a different predetermined length of strip material has been advanced by the gripper carriage, whereby the advancing strip material is caused to slow down before coming to a full stop.

3. A device according to claim 1 wherein said controllable valve means is a solenoid actuated valve which is controlled by means of a limit switch positioned to engage the carriage.

4. A device according to claim 1 wherein said controllable valve means is a solenoid actuated valve which is controlled by means of an electronic device for measuring the length of strip material advanced.

5. A device according to claim 1 wherein said controllable valve means is a pneumatic valve.

6. A device according to claim 1 wherein the power cylinder is an air cylinder.

7. A device according to claim 1 wherein the power cylinder is a hydraulic cylinder.

8. A device according to claim 6 wherein said hydraulic cylinder is powered by means of a pump driven by an electric motor.

9. A device according to claim 8 wherein the pump is connected to the hydraulic power cylinder via a pressure release valve and fluid reservoir.

10. A device according to claim 1 wherein an adjustable valve is provided for controlling the volume of flow through said first controllable valve means.

11. A device according to claim 2 wherein an adjustable valve is provided for controlling the volume of flow through said second controllable valve means.

12. In a device for intermittently advancing strip material into a production machine and including a base having a carriage member slidably mounted thereon, a gripper on said carriage member for engaging and holding strip material thereto and power cylinder means mounted on said base for slidably reciprocating said carriage member, the improvement which comprises:

a. a hydraulic plunger-cylinder means connected between said carriage and base, whereby movement of the carriage causes relative movement between the plunger and cylinder,

b. a first fluid conduit connecting said hydraulic cylinder to a fluid reservoir and including check valve means,

c. a second fluid conduit connecting said hydraulic cylinder to said fluid reservoir and including first controllable valve means, and

d. first means for closing said controllable valve when a predetermined length of strip material has been advanced by the gripper carriage, whereby during advance of the gripper carriage, movement of the plunger causes flow of fluid through the second conduit and controllable valve into the reservoir until the valve is closed thereby stopping the plunger and carriage and during return of the carriage; movement of the plunger causes flow of fluid from said reservoir through the first conduit and check valve into said plunger-cylinder.

13. A device according to claim 1 which includes a third fluid conduit connecting said hydraulic cylinder.

to said reservoir, second controllable valve means in said conduit and second means for closing said valve when a different predetermined length of strip material has been advanced by the gripper carriage, whereby the advancing strip material is caused to slow down before coming to a full stop. 

1. In a device for intermittently advancing strip material into a production machine and including a base having a carriage member slidably mounted thereon, a gripper on said carriage member for engaging and holding strip material thereto and power cylinder means mounted on said base for slidably reciprocating said carriage member, the improvement which comprises: a. a double acting hydraulic plunger-cylinder means connected between said carriage and base, whereby movement of the carriage causes relative movement between the plunger and cylinder, b. a first fluid conduit connecting opposite ends of said hydraulic cylinder and including check valve means, c. a second fluid conduit connecting opposite ends of said hydraulic cylinder and including first controllable valve means, and d. first means for closing said controllable valve when a predetermined length of strip material has been advanced by the gripper carriage, whereby during advance of the gripper carriage, movement of the plunger causes flow of fluid through the second conduit and cOntrollable valve until the valve is closed thereby stopping the plunger and carriage and during return of the carriage, movement of the plunger causes flow of fluid through the first conduit and check valve.
 2. A device according to claim 1 which includes a third fluid conduit connecting opposite ends of said hydraulic cylinder, second controllable valve means in said conduit and second means for closing said valve when a different predetermined length of strip material has been advanced by the gripper carriage, whereby the advancing strip material is caused to slow down before coming to a full stop.
 3. A device according to claim 1 wherein said controllable valve means is a solenoid actuated valve which is controlled by means of a limit switch positioned to engage the carriage.
 4. A device according to claim 1 wherein said controllable valve means is a solenoid actuated valve which is controlled by means of an electronic device for measuring the length of strip material advanced.
 5. A device according to claim 1 wherein said controllable valve means is a pneumatic valve.
 6. A device according to claim 1 wherein the power cylinder is an air cylinder.
 7. A device according to claim 1 wherein the power cylinder is a hydraulic cylinder.
 8. A device according to claim 6 wherein said hydraulic cylinder is powered by means of a pump driven by an electric motor.
 9. A device according to claim 8 wherein the pump is connected to the hydraulic power cylinder via a pressure release valve and fluid reservoir.
 10. A device according to claim 1 wherein an adjustable valve is provided for controlling the volume of flow through said first controllable valve means.
 11. A device according to claim 2 wherein an adjustable valve is provided for controlling the volume of flow through said second controllable valve means.
 12. In a device for intermittently advancing strip material into a production machine and including a base having a carriage member slidably mounted thereon, a gripper on said carriage member for engaging and holding strip material thereto and power cylinder means mounted on said base for slidably reciprocating said carriage member, the improvement which comprises: a. a hydraulic plunger-cylinder means connected between said carriage and base, whereby movement of the carriage causes relative movement between the plunger and cylinder, b. a first fluid conduit connecting said hydraulic cylinder to a fluid reservoir and including check valve means, c. a second fluid conduit connecting said hydraulic cylinder to said fluid reservoir and including first controllable valve means, and d. first means for closing said controllable valve when a predetermined length of strip material has been advanced by the gripper carriage, whereby during advance of the gripper carriage, movement of the plunger causes flow of fluid through the second conduit and controllable valve into the reservoir until the valve is closed thereby stopping the plunger and carriage and during return of the carriage, movement of the plunger causes flow of fluid from said reservoir through the first conduit and check valve into said plunger-cylinder.
 13. A device according to claim 1 which includes a third fluid conduit connecting said hydraulic cylinder to said reservoir, second controllable valve means in said conduit and second means for closing said valve when a different predetermined length of strip material has been advanced by the gripper carriage, whereby the advancing strip material is caused to slow down before coming to a full stop. 